Programmable electronic energy meters are rapidly replacing electro-mechanical meters due to the enhanced functionality achieved using programmable logic integrated into solid-state electronic meters. Some of these meters can be used to meter various different electrical services without hardware modification. For example, meters having a voltage operating range between 98 Vrms to 526 Vrms are capable of operation with either 120 V or 480 V services. U.S. Pat. No. 5,457,621, dated Oct. 10, 1995, entitled SWITCHING POWER SUPPLY HAVING VOLTAGE BLOCKING CLAMP, assigned to ABB Power T&D Company discloses examples of such meters. In addition, some meters are constructed for use with any 3-wire or any 4-wire service, also disclosed in U.S. Pat. No. 5,457,621. Unless meters having this versatility are used, utilities must be careful to install the correct meter in relation to both configuration and electrical service supplied at the installation site. Unfortunately, meter installers are not always trained to detect or note service particularities which might indicate that the meter to be installed is not configured properly for a particular installation.
For this reason, some utilities configure the meters themselves to ensure better control over which meters are installed at which installation sites. However, such configuration activity adds to the installation cost and does not always reduce the risk that a meter configured for one service might inadvertently be installed at a site supplied by a different service. Therefore, there remains a need for an electronic meter which automatically detects the service type and voltage to which the meter is installed and which either automatically configures its own programming to the detected service or provides a simple means for manual configuration at the installation site.
Further, the performance of power quality tests requires that the type of service and service voltage be known prior to installation so that the meter's programming can be locked to the appropriate service-dependent thresholds utilized in connection with particularized power quality tests. Therefore, for this additional reason, there remains a need for an electronic meter to automatically detect the service type and voltage to which the meter is installed and which automatically configures its programming to the detected service.
In addition, many new electronic energy meters have begun to take advantage of their programming capabilities by providing limited diagnostic and/or power quality testing. These capabilities are provided by programming stored in read only memory (ROM). Thus, these meters are currently limited in operation to predefined programming, such as predefined sets of tests. Significantly, such meters are also limited to the measurement of only a predetermined set of parameters that have been programmed into such meters, i.e., stored in ROM, during manufacture. Consequently, any change to the measurements or tests supported by the meter must be carried out by replacing the meter's ROM, i.e., by factory modification. Therefore, there also exists a need for a more flexible electronic energy meter that permits the addition of new measurements or testing capabilities without requiring factory modifications to effect such functionality changes.